A construction worker walks into a bar. He's a rather large, menacing guy. He orders a beer, chugs it back, and bellows, "All you guys on this side of the bar are a bunch of idiots!" A sudden silence descends. After a moment, he asks, "Anyone got a problem with that?" The silence lengthens.
He then chugs back another beer, and growls, "And all you guys on the other side of the bar are scum!" Once again, the bar is silent. He looks around belligerently, and roars, "Anyone got a problem with that?"
A lone man gets up from his stool, and starts to walk towards the construction worker who yells, "You got a problem, buddy?" The man replies, "Oh no. I'm just on the wrong side of the bar."